Coal-fired electric utility power plants may produce solid waste, slurry waste, and flue gas, which may be emitted to the atmosphere. Coal-fired power plants may remove sulfur dioxide (SO2) from the flue gas by using flue gas desulfurization systems. An example of a flue gas desulfurization system is a wet scrubber. Wet scrubber systems may inject aqueous slurry of an alkaline sorbent, such as limestone (CaCO3) and a lime-based slurry (Ca(OH)2), into the flue gas to capture the SO2 and produce flue gas desulfurization scrubber effluent.
The flue gas desulfurization scrubber effluent may include a mixture of liquid waste and solid waste, such as calcium sulfite, calcium sulfate, chlorides, heavy metals and other by-products. The effluent may be disposed in a landfill or an impoundment. However, this may create secondary environmental risks, such as pollution of ground liquid and surface liquid, e.g., water, due to infiltration into underlying soils and free liquid emitting to the surface as well as a potential breach of the impoundment resulting in uncontrolled spills. Proposed regulations by some federal and state agencies may restrict or prohibit disposal of the flue gas desulfurization scrubber effluent into impoundments. Other conventional methods may require drying the effluent and transporting the dried effluent by conveyor or truck to the landfill which may also require additional spreading and compaction.
Accordingly, more efficient and/or cost-effective methods for treating flue gas desulfurization scrubber effluent are desirable.